How it is implemented could possibly mean how rings intersect (my hunch) which would thus implicate all CN coins. He may be saying that the encryption of one ring is not breakable, but the correlation of multiple rings leads to a discovery of the 'x' private key in the NIZKP. I shouldn't be so lazy and should actually try to do the math to see if my hunch is correct. There are other probably other possibilities as well. I can't be sure my hunch is the correct one, as I haven't done the math (yet).